Display device

ABSTRACT

According to one embodiment, a display device includes a first substrate including a first resin substrate having a first thermal expansion coefficient, and a first barrier layer having a second thermal expansion coefficient which is lower than the first thermal expansion coefficient, a second substrate including a second resin substrate having a third thermal expansion coefficient which is equal to the first thermal expansion coefficient, and a second barrier layer having a fourth thermal expansion coefficient which is lower than the third thermal expansion coefficient and is equal to the first thermal expansion coefficient, and a display element located between the first resin substrate and the second resin substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityunder 35 U.S.C. § 120 from U.S. application Ser. No. 16/533,903 filedAug. 7, 2019, which is a continuation of U.S. application Ser. No.15/826,946 filed Nov. 30, 2017 (now U.S. Pat. No. 10,416,485 issued Sep.17, 2019), which is a division of U.S. application Ser. No. 14/164,912filed Jan. 27, 2014, and claims the benefit of priority under 35 U.S.C.§ 119 from Japanese Patent Application No. 2013-030997 filed Feb. 20,2013, the entire contents of each of which are incorporated herein byreference.

FIELD

Embodiments described herein relate generally to a display device.

BACKGROUND

Display devices including organic electroluminescence (EL) elements orliquid crystal elements have been used in various fields. A displaydevice is constructed by stacking a plurality of members. In such adisplay device, there is a concern that a warp occurs due to adifference in thermal expansion coefficient between the respectivemembers.

For example, as regards an optical sheet in which a plurality of opticalelements, which are formed of materials with different thermal expansioncoefficients, are adhered or attached, there is known a technique ofreducing a warp by providing a warp prevention layer having a thermalexpansion coefficient which is equal to a thermal expansion coefficientof an optical functional member. In addition, as regards an organic ELdevice configured such that a warp-reducing substrate, which is opposedto a light emission element provided on a substrate body formed ofglass, and a warp-reducing substrate disposed on that surface of thesubstrate body, which is not opposed to the light emission element, areattached, there is also known a technique in which the two warp-reducingsubstrates are formed of materials having an equal thermal expansioncoefficient, and the thermal expansion coefficient of the materials isclose to the thermal expansion coefficient of the substrate body,thereby reducing a warp. Furthermore, as regards a semiconductor devicein which a semiconductor chip is bonded on a substrate, there is known atechnique in which a warp prevention sheet, which is bonded to the othersurface of the semiconductor chip, and the substrate have substantiallyequal thermal expansion coefficients, thereby preventing a warp of thesemiconductor device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view which schematically illustrates astructure example of a display device 1 of an embodiment.

FIG. 1B is a cross-sectional view which schematically illustratesanother structure example of the display device 1 of the embodiment.

FIG. 1C is a cross-sectional view which schematically illustratesanother structure example of the display device 1 of the embodiment.

FIG. 2 schematically illustrates a state in which a stress occurs ineach of an array substrate AR and a counter-substrate CT in the displaydevice 1 of the embodiment.

FIG. 3 is a view for describing a manufacturing method of the displaydevice 1 of the embodiment, illustrating a step of preparing a firstmother substrate M1.

FIG. 4 is a view for describing the manufacturing method of the displaydevice 1 of the embodiment, illustrating a step of preparing a secondmother substrate M2.

FIG. 5 is a view for describing a step of coating a sealant SE and anadhesive 40.

FIG. 6 is a view for describing the manufacturing method of the displaydevice 1 of the embodiment, illustrating a step of attaching the firstmother substrate M1 and the second mother substrate M2.

FIG. 7 is a view for describing the manufacturing method of the displaydevice 1 of the embodiment, illustrating a step of peeling a firstsupport substrate 100 of the first mother substrate M1 and a secondsupport substrate 200 of the second mother substrate M2.

FIG. 8 is a view for describing the manufacturing method of the displaydevice 1 of the embodiment, illustrating a step of cutting a first resinsubstrate 10.

DETAILED DESCRIPTION

In general, according to one embodiment, a display device includes: afirst substrate including a first resin substrate having a first thermalexpansion coefficient, a first barrier layer which covers an innersurface of the first resin substrate and has a second thermal expansioncoefficient which is lower than the first thermal expansion coefficient,and a switching element formed above the first barrier layer; a secondsubstrate including a second resin substrate which is formed of amaterial different from a material of the first resin substrate and hasa third thermal expansion coefficient which is equal to the firstthermal expansion coefficient, a second barrier layer which covers aninner surface of the second resin substrate and has a fourth thermalexpansion coefficient which is lower than the third thermal expansioncoefficient and is equal to the first thermal expansion coefficient; anda display element located between the first resin substrate and thesecond resin substrate and including a pixel electrode which iselectrically connected to the switching element.

FIG. 1A is a cross-sectional view which schematically illustrates astructure example of a display device 1 of the embodiment. A descriptionis given of a cross-sectional structure of an organic EL display deviceas an example of the display device 1.

The illustrated organic EL display device 1 adopts an active matrixdriving method, and includes an array substrate AR and acounter-substrate CT. The array substrate AR is formed by using a firstresin substrate 10. The array substrate AR includes, on an inner surface10A side of the first resin substrate 10, a first insulation film 11, asecond insulation film 12, a third insulation film 13, a fourthinsulation film 14, ribs 15, switching elements SW1 to SW3, and organicEL elements OLED1 to OLED3 functioning as display elements.

The first resin substrate 10 is an insulative substrate, which is formedof, for example, a material consisting mainly of polyimide (PI). Thefirst resin substrate 10 has a thickness of, e.g. 5 to 30 μm. As thematerial for forming the first resin substrate 10, a material with ahigh heat resistance, such as polyamide-imide or polyaramide, as well aspolyimide, is selected. Specifically, the first resin substrate 10 isoften exposed to a high-temperature process in the formation of variousinsulation films, the formation of switching elements, and the formationof organic EL elements. Thus, the most important property, which isrequired for the first resin substrate 10, is a high heat resistance. Aswill be described later, the organic EL element is of a so-called topemission type which emits light via the counter-substrate CT.Accordingly, it is not always necessary that the first resin substrate10 have high transparency, and the first resin substrate 10 may becolored.

The inner surface 10A of the first resin substrate 10 is covered withthe first insulation film 11. The first insulation film 11 functions asa first barrier layer for suppressing entrance of ionic impurities fromthe first resin substrate 10 or entrance of moisture via the first resinsubstrate 10. The first insulation film 11 is formed of an inorganicmaterial including silicon as a main component, such as silicon nitride(SiN), silicon oxide (SiO) or silicon oxynitride (SiON), and is composedof a single layer or a multilayer. For example, the first insulationfilm 11 is formed of a multilayer body in which silicon nitride andsilicon oxide are alternately stacked. Incidentally, the firstinsulation film 11 may be formed of some other material which can ensurea barrier capability.

The switching elements SW1 to SW3 are formed on the first insulationfilm 11. The switching elements SW1 to SW3 are, for example, thin-filmtransistors (TFTs) each including a semiconductor layer SC. Theswitching elements SW1 to SW3 have the same structure. In thedescription below, attention is paid to the switching element SW1, andthe structure thereof is described more specifically.

In the example illustrated, the switching element SW1 is of a top gatetype, but may be of a bottom gate type. The semiconductor layer SC isformed of a silicon-based material such as amorphous silicon orpolysilicon, or an oxide semiconductor which is an oxide including atleast one of indium (In), gallium (Ga) and zinc (Zn).

The semiconductor layer SC is formed on the first insulation film 11,and is covered with a second insulation film 12. The second insulationfilm 12 is also disposed on the first insulation film 11. A gateelectrode WG of the switching element SW1 is formed on the secondinsulation film 12. The gate electrode WG is covered with a thirdinsulation film 13. The third insulation film 13 is also disposed on thesecond insulation film 12.

A source electrode WS and a drain electrode WD of the switching elementSW1 are formed on the third insulation film 13. The source electrode WSis put in contact with a source region of the semiconductor layer SC.The drain electrode WD is put in contact with a drain region of thesemiconductor layer SC. The source electrode WS and drain electrode WDare covered with a fourth insulation film 14. The fourth insulation film14 is also disposed on the third insulation film 13.

The organic EL elements OLED1 to OLED3 are formed on the fourthinsulation film 14. In the example illustrated, the organic EL elementOLED1 is electrically connected to the switching element SW1, theorganic EL element OLED2 is electrically connected to the switchingelement SW2, and the organic EL element OLED3 is electrically connectedto the switching element SW3. The color of emission light of each of theorganic EL elements OLED1 to OLED3 is white. The organic EL elementsOLED1 to OLED3 have the same structure.

The organic EL element OLED1 includes a pixel electrode PE1 which isformed on the fourth insulation film 14. The pixel electrode PE1 is incontact with the drain electrode WD of the switching element SW1 and iselectrically connected to the switching element SW1. Similarly, theorganic EL element OLED2 includes a pixel electrode PE2 which iselectrically connected to the switching element SW2, and the organic ELelement OLED3 includes a pixel electrode PE3 which is electricallyconnected to the switching element SW3. The pixel electrodes PE1 to PE3function as, for example, anodes. The pixel electrodes PE1 to PE3 may beformed of a transparent, electrically conducive material such as indiumtin oxide (ITO) or indium zinc oxide (IZO), or may be formed of ametallic material such as aluminum (Al), magnesium (Mg), silver (Ag),titanium (Ti), or an alloy thereof. In the case of the top emissiontype, it is desirable that the pixel electrodes PE1 to PE3 includereflective layers formed of a metallic material with a highreflectivity.

The organic EL elements OLED1 to OLED3 further include an organic lightemission layer ORG and a common electrode CE. The organic light emissionlayer ORG is located on the pixel electrodes PE1 to PE3. In addition,the organic light emission layer ORG is continuously formed, without abreak, over the organic EL elements OLED1 to OLED3. The common electrodeCE is located on the organic light emission layer ORG. In addition, thecommon electrode CE is continuously formed, without a break, over theorganic EL elements OLED1 to OLED3. The common electrode CE is formedof, for example, a transparent, electrically conductive material such asITO or IZO.

Specifically, the organic EL element OLED1 is composed of the pixelelectrode PE1, organic light emission layer ORG and common electrode CE.The organic EL element OLED2 is composed of the pixel electrode PE2,organic light emission layer ORG and common electrode CE. The organic ELelement OLED3 is composed of the pixel electrode PE3, organic lightemission layer ORG and common electrode CE.

In the meantime, in the organic EL elements OLED1 to OLED3, a holeinjection layer or a hole transport layer may be further providedbetween each of the pixel electrodes PE1 to PE3 and the organic lightemission layer ORG, and an electron injection layer or an electrontransport layer may be further provided between the organic lightemission layer ORG and the common electrode CE.

The organic EL elements OLED1 to OLED3 are partitioned by the ribs 15.The ribs 15 are formed on the fourth insulation film 14 and cover theedges of the pixel electrodes PE1 to PE3. The ribs 15 are formed, forexample, in a grid shape or in a stripe shape on the fourth insulationfilm 14. The ribs 15 are covered with the organic light emission layerORG. Specifically, the organic light emission layer ORG extends over notonly the pixel electrodes PE1 to PE3 but also over the ribs 15.

In the example illustrated, the organic EL elements OLED1 to OLED3 aresealed by a sealing film 20. The sealing film 20 functions as a barrierfilm which protects the organic EL elements OLED1 to OLED3 fromcontaminants such as moisture, oxygen and hydrogen. The sealing film 20is formed of an inorganic material including silicon as a maincomponent, such as silicon nitride (SiN), silicon oxide (SiO) or siliconoxynitride (SiON), and is composed of a single layer or a multilayer.

The counter-substrate CT is formed by using a transparent second resinsubstrate 30. The counter-substrate CT includes a fifth insulation film31, a blue color filter 32B, a green color filter 32G and a red colorfilter 32R on an inner surface 30A side of the second resin substrate30.

The second resin substrate 30 is a transparent resin substrate, which isformed of, for example, a material consisting mainly of polyimide (PI).The second resin substrate 30 has a thickness which is equal to thethickness of the first resin substrate 10, for example, a thickness of 5to 30 μm. As the material for forming the second resin substrate 30, amaterial with high transparency is selected. Specifically, light emittedfrom the organic EL elements OLED1 to OLED3 of the top emission typepasses through the second resin substrate 30. Thus, the most importantproperty, which is required for the second resin substrate 30, is a hightransparency. In this manner, the property that is required is differentbetween the first resin substrate 10 and the second resin substrate 30.Thus, the second resin substrate 30 is formed of a material which isdifferent from the material of the first resin substrate 10. Forexample, the first resin substrate 10 is formed by using an opaquepolyimide with good heat resistance, and the second resin substrate 30is formed by using a transparent polyimide.

The inner surface 30A of the second resin substrate 30 is covered with afifth insulation film 31. The fifth insulation film 31 functions as asecond barrier layer for suppressing entrance of ionic impurities fromthe second resin substrate 30 or entrance of moisture via the secondresin substrate 30. The fifth insulation film 31 is formed of aninorganic material including silicon as a main component, such assilicon nitride (SiN), silicon oxide (SiO) or silicon oxynitride (SiON),and is composed of a single layer or a multilayer. For example, thefifth insulation film 31 has the same structure as the first insulationfilm 11, and is formed of a multilayer body in which silicon nitride andsilicon oxide are alternately stacked.

The thermal expansion coefficient of the second resin substrate 30 issubstantially equal to the thermal expansion coefficient of the firstresin substrate 10. In addition, the thermal expansion coefficient ofthe fifth insulation film 31 is substantially equal to the thermalexpansion coefficient of the first insulation film 11. Besides, thethermal expansion coefficients of the fifth insulation film 31 and firstinsulation film 11 are lower than the thermal expansion coefficients ofthe first resin substrate 10 and second resin substrate 30. For example,each of the thermal expansion coefficients of the fifth insulation film31 and first insulation film 11 is 0.5 to 3 ppm/° C., and each of thethermal expansion coefficients of the first resin substrate 10 andsecond resin substrate 30 is 20 to 50 ppm/° C. The thermal expansioncoefficients of the first resin substrate 10, second resin substrate 30,fifth insulation film 31 and first insulation film 11 are so set as tomeet the above-described relationship, and thereby a warp of the displaydevice 1 can be prevented.

The blue color filter 32B is opposed to the organic EL element OLED1 andpasses a light component of a blue wavelength of white light. The greencolor filter 32G is opposed to the organic EL element OLED2 and passes alight component of a green wavelength of white light. The red colorfilter 32R is a red color filter which is opposed to the organic ELelement OLED3 and passes a light component of a red wavelength of whitelight. Boundaries between the neighboring color filters are locatedabove the ribs 15.

The above-described array substrate AR and counter-substrate CT areattached by a sealant which attaches the array substrate AR andcounter-substrate CT on an outside of a display section which displaysan image. A transparent filler 40 is sealed between the array substrateAR and counter-substrate CT. Specifically, the organic EL elements OLED1to OLED3 are located between the first resin substrate 10 and secondresin substrate 30. In the example illustrated, the sealing film 20 andfiller 40 are interposed between the organic EL element OLED1 and bluecolor filter 32B, between the organic EL element OLED2 and green colorfilter 32G and between the organic EL element OLED3 and red color filter32R. It is desirable that the filler 40 be formed of a material having amoisture-absorbing capability. Thereby, even if a defect occurs in thesealing film 20, the filler 40 enters the defect of the sealing film 20,and can block a moisture entrance path.

Incidentally, the array substrate AR and counter-substrate CT may beattached by an adhesive having a moisture-absorbing capability, in placeof the filler.

According to the above-described organic EL display device that is anexample of the display device 1, when each of the organic EL elementsOLED1 to OLED3 has emitted light, this radiated light (white light) isemitted to the outside via the blue color filter 32B, green color filter32G or red color filter 32R. At this time, a light component of a bluewavelength of the white light, which has been radiated from the organicEL element OLED1, passes through the blue color filter 32B. In addition,a light component of a green wavelength of the white light, which hasbeen radiated from the organic EL element OLED2, passes through thegreen color filter 32G. A light component of a red wavelength of thewhite light, which has been radiated from the organic EL element OLED3,passes through the red color filter 32R. Thereby, color display isrealized.

Next, other structure examples of the display device 1 of the embodimentwill be described.

FIG. 1B is a cross-sectional view which schematically illustratesanother structure example of the display device 1 of the embodiment.

The illustrated structure example differs from the structure exampleshown in FIG. 1A in that the color filter of the counter-substrate CT isomitted, and the organic EL elements OLED1 to OLED3 emit lights ofdifferent colors. The same structure as in the structure example shownin FIG. 1A is denoted by like reference numerals, and a detaileddescription thereof is omitted.

Specifically, the array substrate AR includes a first resin substrate10, a first insulation film 11, a second insulation film 12, a thirdinsulation film 13, a fourth insulation film 14, ribs 15, switchingelements SW1 to SW3, organic EL elements OLED1 to OLED3, and a sealingfilm 20. The thermal expansion coefficient of the first insulation film11 is lower than the thermal expansion coefficient of the first resinsubstrate 10.

The organic EL element OLED1 is composed of a pixel electrode PE1 whichis connected to the switching element SW1, an organic light emissionlayer ORG(B) which is located above the pixel electrode PE1, and acommon electrode CE which is located above the organic light emissionlayer ORG(B). The organic EL element OLED2 is composed of a pixelelectrode PE2 which is connected to the switching element SW2, anorganic light emission layer ORG(G) which is located above the pixelelectrode PE2, and the common electrode CE which is located above theorganic light emission layer ORG(G). The organic EL element OLED3 iscomposed of a pixel electrode PE3 which is connected to the switchingelement SW3, an organic light emission layer ORG(R) which is locatedabove the pixel electrode PE3, and the common electrode CE which islocated above the organic light emission layer ORG(R).

The organic light emission layer ORG(B) emits blue light, the organiclight emission layer ORG(G) emits green light, and the organic lightemission layer ORG(R) emits red light. The organic light emission layerORG(B), the organic light emission layer ORG(G) and the organic lightemission layer ORG(R) are made discontinuous at locations above the ribs15. The common electrode CE is continuously formed, without a break,over the organic EL elements OLED1 to OLED3, and also covers the ribs15.

The counter-substrate CT includes a second resin substrate 30 and afifth insulation film 31. The second resin substrate 30 is formed of,for example, a transparent polyimide, and the first resin substrate 10is formed of, for example, an opaque polyimide with good heatresistance.

The thermal expansion coefficient of the first resin substrate 10 issubstantially equal to the thermal expansion coefficient of the secondresin substrate 30, and the thermal expansion coefficient of the firstinsulation film 11 is substantially equal to the thermal expansioncoefficient of the fifth insulation film 31. In addition, the thermalexpansion coefficients of the first insulation film 11 and fifthinsulation film 31 are lower than the thermal expansion coefficients ofthe first resin substrate 10 and second resin substrate 30. For example,each of the thermal expansion coefficients of the first insulation film11 and fifth insulation film 31 is 0.5 to 3 ppm/° C., and each of thethermal expansion coefficients of the first resin substrate 10 andsecond resin substrate 30 is 20 to 50 ppm/° C. As has been describedabove, the thermal expansion coefficients of the first resin substrate10, second resin substrate 30, first insulation film 11 and fifthinsulation film 31 are so set as to meet the above-describedrelationship, and thereby a warp of the display device 1 can beprevented.

The above-described array substrate AR and counter-substrate CT areattached.

FIG. 1C is a cross-sectional view which schematically illustratesanother structure example of the display device 1 of the embodiment. Adescription is given of a cross-sectional structure of a liquid crystaldisplay device as an example of the display device 1.

The illustrated structure example differs from the structure exampleshown in FIG. 1A in that this illustrated structure example includesliquid crystal elements as display elements. The same structure as inthe structure example shown in FIG. 1A is denoted by like referencenumerals, and a detailed description thereof is omitted.

Specifically, the array substrate AR includes a first resin substrate10, a first insulation film 11, a second insulation film 12, a thirdinsulation film 13, a fourth insulation film 14, switching elements SW1to SW3, pixel electrodes PE1 to PE3, and a first alignment film AL1. Thethermal expansion coefficient of the first insulation film 11 is lowerthan the thermal expansion coefficient of the first resin substrate 10.

The pixel electrode PE1 is connected to the switching element SW1, thepixel electrode PE2 is connected to the switching element SW2, and thepixel electrode PE3 is connected to the switching element SW3. The firstalignment film AL1 covers the pixel electrodes PE1 to PE3.

The counter-substrate CT includes a second resin substrate 30, a fifthinsulation film 31, a blue color filter 32B, a green color filter 32G, ared color filter 32R, a common electrode CE, and a second alignment filmAL2. The second resin substrate 30 is formed of a material which isdifferent from the material of the first resin substrate 10. Forexample, the second resin substrate 30 is formed of a transparentpolyimide, and the first resin substrate 10 is formed of an opaquepolyimide with good heat resistance.

The thermal expansion coefficient of the first resin substrate 10 issubstantially equal to the thermal expansion coefficient of the thirdresin substrate 30, and the thermal expansion coefficient of the firstinsulation film 11 is substantially equal to the thermal expansioncoefficient of the fifth insulation film 31. In addition, the thermalexpansion coefficients of the first insulation film 11 and fifthinsulation film 31 are lower than the thermal expansion coefficients ofthe first resin substrate 10 and second resin substrate 30. For example,each of the thermal expansion coefficients of the first insulation film11 and fifth insulation film 31 is 0.5 to 3 ppm/° C., and each of thethermal expansion coefficients of the first resin substrate 10 andsecond resin substrate 30 is 20 to 50 ppm/° C. As has been describedabove, the thermal expansion coefficients of the first resin substrate10, second resin substrate 30, first insulation film 11 and fifthinsulation film 31 are so set as to meet the above-describedrelationship, and thereby a warp of the display device 1 can beprevented.

The blue color filter 32B is located above the pixel electrode PE1, thegreen color filter 32G is located above the pixel electrode PE2, and thered color filter 32R is located above the pixel electrode PE3. Thecommon electrode CE is opposed to each of the pixel electrodes PE1 toPE3. The second alignment film AL2 covers the common electrode CE.

The array substrate AR and counter-substrate CT are attached by anadhesive (or sealant) in the state in which a predetermined cell gap iscreated by spacers (not shown). A liquid crystal layer LQ is held in thecell gap between the array substrate AR and counter-substrate CT. Theliquid crystal layer LQ includes liquid crystal molecules, the alignmentstate of which is controlled by an electric field between the pixelelectrodes PE and the common electrode CE.

A liquid crystal element LC1 is composed of the pixel electrode PE1,liquid crystal layer LQ and common electrode CE. A liquid crystalelement LC2 is composed of the pixel electrode PE2, liquid crystal layerLQ and common electrode CE. A liquid crystal element LC3 is composed ofthe pixel electrode PE3, liquid crystal layer LQ and common electrodeCE.

In the example illustrated, the case has been described that the pixelelectrodes PE1 to PE3, which constitute the respective liquid crystalelements, are provided on the array substrate AR and the commonelectrode CE is provided on the counter-substrate CT. Alternatively,both the pixel electrodes PE1 to PE3 and the common electrode CE may beprovided on the array substrate Ar.

According to the present embodiment, the display device 1 is configuredsuch that the first resin substrate 10 and second resin substrate 30 areapplied. Thus, compared to a display device to which glass substratesare applied, the reduction in thickness and weight can be realized, theflexibility is high, and the degree of freedom in shape is high. Inaddition, although the first resin substrate 10 and second resinsubstrate 30 have relatively high moisture absorption properties, theinner surface 10A of the first resin substrate 10 is covered with thefirst insulation film 11 that is the first barrier layer, and the innersurface 30A of the second resin substrate 30 is covered with the fifthinsulation film 31 that is the second barrier layer. Thus, the entranceof moisture, etc. via the first resin substrate 10 or second resinsubstrate 30 can be suppressed. Thereby, it is possible to suppressdegradation due to moisture, etc. of the display elements locatedbetween the first resin substrate 10 and second resin substrate 30.

In addition, the first resin substrate 10, which constitutes the arraysubstrate AR, is formed of, for example, an opaque polyimide with goodheat resistance, and the second resin substrate 30, which constitutesthe counter-substrate CT, is formed of, for example, a transparentpolyimide, which is different from the material of the first resinsubstrate 10. Moreover, the thermal expansion coefficient of the firstresin substrate 10 is equal to the thermal expansion coefficient of thesecond resin substrate 30. Thus, even if the display device 1 isthermally expanded, there is little difference in thermal expansioncoefficient between the first resin substrate 10 and the second resinsubstrate 30. Therefore, the occurrence of a warp of the display device1 can be suppressed.

Furthermore, the first insulation film (first barrier layer) 11, whichcovers the inner surface 10A of the first resin substrate 10, has alower thermal expansion coefficient than the first resin substrate 10.In addition, the fifth insulation film (second barrier layer) 31, whichcovers the inner surface 30A of the second resin substrate 30, has alower thermal expansion coefficient than the second resin substrate 30.The difference in thermal expansion coefficient between the first resinsubstrate 10 and first insulation film 11 is equal to the difference inthermal expansion coefficient between the second resin substrate 30 andfifth resin substrate 31. Thus, although stresses occur in both thearray substrate AR and counter-substrate CT, these stresses are balancedand therefore the occurrence of a warp of the display device 1 can besuppressed. Hence, the shape of the display device 1 can stably bemaintained.

Besides, since the thickness of the first resin substrate 10 is equal tothe thickness of the second resin substrate 30, the variation indimension due to thermal expansion is equal between the first resinsubstrate 10 and second resin substrate 30, and the shape of the displaydevice 1 can further be stabilized.

In FIG. 2, arrows schematically illustrate a relationship between thethermal expansion coefficients of the first resin substrate 10, firstinsulation film 11, second resin substrate 30 and fifth insulation film31 in the array substrate AR and counter-substrate CT in the displaydevice 1 of the embodiment.

In the manufacturing process of the display device 1 of the embodiment,the first resin substrate 10, first insulation film 11, second resinsubstrate 30 and fifth insulation film 31 are formed in a state ofrelatively high temperatures. At this time, since the thermal expansioncoefficients of the first resin substrate 10 and second resin substrate30 are higher than the thermal expansion coefficients of the firstinsulation film 11 and fifth insulation film 31, the first resinsubstrate 10 and second resin substrate 30 are, at a time immediatelyafter the display device 1 has been formed at high temperatures, areformed with a predetermined size in the state in which the first resinsubstrate 10 and second resin substrate 30 are expanded to a greaterdegree than the first insulation film 11 and fifth insulation film 31.The ratio of contraction of the first resin substrate 10 and secondresin substrate 30 at a time when the display device 1 has been cooledfrom the high-temperature state is greater than the ratio of contractionof the first insulation film 11 and fifth insulation film 31.

Accordingly, as the display device 1 which was formed at hightemperatures is cooled, a stress occurs in the peripheral part of thearray substrate AR such that the peripheral part of the array substrateAR warps toward the outside of the first resin substrate 10 (i.e. to aside away from the counter-substrate CT). On the other hand, a stresssimilarly occurs in the counter-substrate CT such that the peripheralpart of the counter-substrate CT warps toward the outside of the secondresin substrate 30 (i.e. to a side away from the array substrate AR). Inaddition, the thermal expansion coefficients of the first resinsubstrate 10 and second resin substrate 30 are equal, and the thermalexpansion coefficients of the first insulation film 11 and fifthinsulation film 31 are equal. Thus, such a stress as to cause an outwardwarp on the array substrate AR side is substantially equal to such astress as to cause an outward warp on the counter-substrate CT side.

As has been described above, although stresses occur in both the arraysubstrate AR and counter-substrate CT, these stresses substantiallyequally act in such direction as to make the array substrate AR andcounter-substrate CT closer to each other, and therefore the shape ofthe display device 1 can be maintained. In addition, when thetemperature of the environment of use of the display device 1 is low,since such stresses as to cause outward warps equally occur in both thearray substrate AR and counter-substrate CT, the shape of the displaydevice 1 can be maintained. Even when the temperature of the environmentof use of the display device 1 is high, stresses have been acting tocause outward warps since before. Thus, the shape of the display device1 can be maintained as long as the temperature of use exceeds thetemperature in the manufacturing process. As regards the organic ELdisplay device as shown in FIG. 1A and FIG. 1B, even when the adhesionforce of the adhesive for attaching the array substrate AR andcounter-substrate CT is weak, the shape of the display device 1 can bemaintained since the stresses occurring in both the array substrate ARand counter-substrate CT act in such directions as to make the arraysubstrate AR and counter-substrate CT closer to each other. As regardsthe liquid crystal display device as shown in FIG. 1C, the shape of thedisplay device 1 can be maintained and the cell gap can be kept sincethe stresses occurring in both the array substrate AR andcounter-substrate CT act in such directions as to press the spacerslying between the array substrate AR and counter-substrate CT, andtherefore degradation in display quality can be suppressed.

In the meantime, a comparative example will now be examined, in whichthe thermal expansion coefficient of the first resin substrate 10 islower than the thermal expansion coefficient of the first insulationfilm 11, and the thermal expansion coefficient of the second resinsubstrate 30 is lower than the thermal expansion coefficient of thefifth insulation film 31. In this comparative example, in the arraysubstrate AR after fabrication, such a stress occurs that the centralpart of the array substrate AR warps toward the outside of the firstresin substrate 10. On the other hand, in the counter-substrate CT afterfabrication, such a stress occurs that the central part of thecounter-substrate CT warps toward the outside of the second resinsubstrate 30. In this manner, the stresses occurring in both the arraysubstrate AR and counter-substrate CT act in such directions as to makethe array substrate AR and counter-substrate CT away from each other atthe central part of the display device 1.

Thus, as regards the organic EL display device as shown in FIG. 1A andFIG. 1B, when the adhesion force between the array substrate AR andcounter-substrate CT is weak, the shape of the display device 1 canhardly be maintained. As regards the liquid crystal display device asshown in FIG. 1C, there is a concern that the degradation in displayquality or the occurrence of bubbles will occur, since the stressesoccurring in both the array substrate AR and counter-substrate CT act insuch directions as to increase the cell gap between the array substrateAR and counter-substrate CT.

As has been described above, according to the display device 1 of thepresent embodiment, the shape can be maintained more stably than in thecomparative example, and the degradation in display quality can besuppressed.

Next, a description is given of an example of a method of manufacturingthe display device 1 according to the embodiment. In the descriptionbelow, an example of the manufacturing method of the display device withthe structure example shown in FIG. 1A will be described.

To begin with, as illustrated in FIG. 3, a first mother substrate M1 isprepared. Specifically, a film of a resin material with a desiredthickness is formed on a first support substrate 100 such as a glasssubstrate. Then, this film is cured, and a first resin substrate 10 isformed. At this time, the first resin substrate 10 extends over a regioncorresponding to the display section, this region being a part of theregion which becomes an individual array substrate after a cutting step(to be described later). In the example illustrated, the first resinsubstrate 10 extends over regions corresponding to three displaysections, namely a first region A1, a second region A2 and a thirdregion A3. Thereafter, on the first resin substrate 10, a thin film ofan inorganic material is formed and, where necessary, a multilayer ofthin films is formed. Thereby, a first insulation film 11 is formed. Thefirst insulation film 11 extends over the first region A1, second regionA2 and third region A3.

Subsequently, a display element part 121 is formed in the first regionA1 on the first insulation film 11, a display element part 122 is formedin the second region A2 on the first insulation film 11, and a displayelement part 123 is formed in the third region A3 on the firstinsulation film 11. In addition, mounting portions 131 to 133 formounting signal supply sources, such as driving IC chips and flexiblecircuit boards, are formed on the first insulation film 11. The displayelement parts 121 to 123 have the same structure, and each of thedisplay element parts 121 to 123 includes a plurality of displayelements, for example, organic EL elements, which are arranged in amatrix.

The display element parts 121 to 123 are formed in the following manner.Specifically, switching elements SW1 to SW3, a second insulation film12, a third insulation film 13 and a fourth insulation film 14 areformed on the first insulation film 11. At the same time, variouswirings are formed. Subsequently, pixel electrodes PE1 to PE3 are formedon the fourth insulation film 14, and then ribs 15 are formed.Thereafter, an organic light emission layer ORG is formed, and a commonelectrode CE is formed. Through these steps, organic EL elements OLED1to OLED3 are formed. Then, where necessary, a sealing film 20, whichcovers the organic EL elements OLED1 to OLED3, is formed.

Subsequently, as illustrated in FIG. 4, a second mother substrate M2 isprepared. Specifically, a film of a resin material with a desiredthickness is formed on a second support substrate 200 such as a glasssubstrate. Thereafter, the film of resin material is cured and thenpatterned by using a photolithography process or the like. Thereby,transparent second resin substrates 30 are formed. The individual secondresin substrates 30 are spaced apart from each other. Specifically, eachof the second resin substrates 30 is formed in an island shape on thesecond support substrate 200.

A thin film of an inorganic material is formed on each of the secondresin substrates 30 and, where necessary, a multilayer of thin films isformed. Thus, fifth insulation films 31 are formed.

A color filter layer CF is formed on each of the fifth insulation films31. The color filter layers CF have the same structure, and each colorfilter layer includes a blue color filter 32B, a green color filter 32Gand a red color filter 32R.

Subsequently, as illustrated in FIG. 5, a frame-shaped sealant SE isformed in each of the first region A1, second region A2 and third regionA3, and then a filler (or an adhesive) 40 is coated in an insidesurrounded by the sealant SE.

Thereafter, as illustrated in FIG. 6, the first mother substrate M1 andsecond mother substrate M2 are attached. Specifically, the respectivedisplay element parts 121 to 123 are attached to the color filter layersCF by the sealant SE and adhesive 40.

Subsequently, as illustrated in FIG. 7, with respect to the secondmother substrate M2, the second support substrate 200 is peeled from thesecond resin substrate 30, and the second support substrate 200 isremoved. Similarly, with respect to the first mother substrate M1, thefirst support substrate 100 is peeled from the first resin substrate 10,and the first support substrate 100 is removed. As regards the peelingand removal of the first support substrate 100 and second supportsubstrate 200, for example, a technology called “laser ablation” isapplicable. The laser ablation is a technique in which a laser beam isradiated on the support substrate, whereby local energy absorptionoccurs at the interface between the support substrate and the resinsubstrate and the support substrate is made separable from the resinsubstrate. An excimer laser, for example, is applicable as the lightsource for emitting the laser beam.

Subsequently, as illustrated in FIG. 8, the first resin substrate 10 iscut. In the example illustrated, the first resin substrate 10 is cutbetween the first region A1 and second region A2 and between the secondregion A2 and third region A3. Thereby, chips C1 to C3 are separated.The chip C1 includes the display element part 121 in the first regionA1, and includes the mounting portion 131 on the outside of the firstregion A1. The chip C2 includes the display element part 122 in thesecond region A2, and includes the mounting portion 132 on the outsideof the second region A2. The chip C3 includes the display element part123 in the third region A3, and includes the mounting portion 133 on theoutside of the third region A3.

Subsequently, a signal supply source is mounted on each of the mountingportions 131 to 133.

Thereby, the display device (organic EL display device) 1 of the presentembodiment is manufactured.

During the above-described manufacturing process, the display device(organic EL display device) 1 of the present embodiment is exposed in ahigh-temperature state. However, as described above, the thermalexpansion coefficients of the first resin substrate 10, second resinsubstrate 30, fifth insulation film 31 and first insulation film 11 areso set as to meet the above-described relationship. Thereby, a warp ofthe display device 1 can be prevented.

As has been described above, according to the present embodiment, adisplay device, which can stably maintain the shape thereof, can beprovided.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

1. (canceled)
 2. A display device comprising: a first substrateincluding a first resin substrate formed of a first resin material, thefirst resin material having a first thermal expansion coefficient; afirst barrier layer formed on the first resin substrate, the firstbarrier layer having a second thermal expansion coefficient; a displayportion formed on the first barrier layer and including a light emittingelement and a sealing film covering the light emitting element; amounting portion formed on the first barrier layer; a second substrateincluding a second resin substrate formed of a second resin material,the second resin material having a third thermal expansion coefficient;and a second barrier layer formed on the second resin substrate, thesecond barrier layer having a fourth thermal expansion coefficient,wherein the first resin substrate and the second resin substrate aretransparent, the second thermal expansion coefficient is lower than thefirst thermal expansion coefficient, the fourth thermal expansioncoefficient is lower than the third thermal expansion coefficient, thefirst resin substrate is in contact with a first surface of the firstbarrier layer, the second resin substrate is in contact with the secondbarrier layer, a switching element is formed on the first barrier layer,the light emitting element is electrically connected to the switchingelement, and the first substrate and the second substrate are attachedto each other with an insulating adhesive.
 3. The display device ofclaim 2, wherein the first thermal expansion coefficient and the thirdthermal expansion coefficient are 20 to 50 ppm/° C.
 4. The displaydevice of claim 2, wherein the second thermal expansion coefficient andthe fourth thermal expansion coefficient are 0.5 to 3.0 ppm/° C.
 5. Thedisplay device of claim 2, wherein the first resin substrate is formedof the first resin material including polyimide as a main component. 6.The display device of claim 2, wherein the first barrier layer is formedof an inorganic material including silicon as a main component.
 7. Thedisplay device of claim 2, wherein the first barrier layer is formed ofa multilayer body in which silicon nitride and silicon oxide arealternately stacked.
 8. The display device of claim 2, wherein theinsulating adhesive does not overlap the mounting portion.
 9. Thedisplay device of claim 2, wherein the insulating adhesive is in contactwith the second barrier layer and the sealing film.
 10. The displaydevice of claim 2, wherein the light emitting element is an organicelectroluminescence element.
 11. The display device of claim 2, whereinthe first thermal expansion coefficient and the third thermal expansioncoefficient are greater than 20 ppm/° C. but less than or equal to 50ppm/° C.
 12. The display device of claim 2, wherein the second thermalexpansion coefficient and the fourth thermal expansion coefficient aregreater than or equal to 0.5 ppm/° C. but less than 3.0 ppm/° C.